Cord locking apparatus for venetian blinds



April 25, 1939. w w LEw|$ 2,155,945-

' CORD LOCKING APPARATUS FOR VENETIAN BLINDS FiledMaroh 17, 1938 IN VEN TOR By [mm/w W. LEWIS 'QQ- W A TTORNEV Patented Apr-. 25, 1939 UNITED STATES- PATENT OFFICE ooantocxmcaiir a a sgusroa wiuiam Weaver Lewis, rm Washington, N. Y, Application March- 11, '1938, Serial No. 196,326

10mm. (01. l5617)' I This invention relates to Venetian blind apparatus, and more particularlyto an automatic device for looking a Venetian blind in desired positions.- f

5 All forms of cord locking devices used a the present time and characterized as automati or self-locking mechanisms include a rotatable locking-member for locking and releasing a cord utilized to raise and lower a Venetian blind. The movement or the cord is translated irom a horizontal to a vertical direction, or vice versa', by

' being passed over a sheave which is operatively associated with the locking-member-to wedge the cord therebetween in such manner that. in tacing the assembled device, the locking-member is disposed on the right-hand side of the vertical portion of the cord accessible to the hand of the operator. In releasing the cord, preliminary to the lowering of a blind, the locking-member is moved in a releasing direction out of contact with the cord solely by the force of gravity and attimes during the lowering of the blind the cord 7 tends to contact the locking-member in the manner described immediately below thereby to be wedged on the sheave in the well known manner to prevent further lowering movement of the blind.

As a blind is being lowered rrom its uppermost or entirely contracted position. the weight of the blind suspended on the cord and opposing a controlling force supplied by an operator to the cord isnormally sumclent to nullify the tendency oi'the cord to come in contact with the locking-member. This, of course, permits a 35 lowering movement of the blind. As the blind approaches its lowermost or fully extended position, the weight thereof is increasingly transterred from the cord to a textile ladder included in the blind thereby correspondingly rglucing the weight-on the cord. Thus, the controlling force supplied'by an operator to the cord is insufllcient as opposed to the reduced weight of the .blind suspended on the cord to overcome the tendency of the cord to come in contact with the locking-member. 7

Consequently, the cord will be wedged between the sheaveand the locking-member to prevent further lowering movement of the blind. As the blind opens gradually from the; top downward 60 the aforementioned locking is caused to occur 1 -inadvertently before the lowermost portion of the blind is extended. Accordinslinthe lowermost portion of the blind will remain unextended until the free end or the cord is by" 55 the operator torelease the inadvertent wedging thereof between the sheave and the locking-mem-- ber. Obviously such situation is not only a uni sauce but it isalso hazardous in that too violent oscillation of the cord by impulsive operators can cause serious damage to the blind assembly." 5

It is an object of the present invention'to provide for a Venetian blind a cord-locking arrangement that allows at all times alowering movement thereof in an 'expeditious'manner until a fully-extended condition is attained. 4 10 It is another object of the invention to providefor a Venetian blind a cord-locking device'that is automatic in operation irrespective of 'the amount of blind that is unextended.

It is a further object of the invention to pro- 15 p vide for a Venetian blind a cord-locking arrangement that precludes inadvertent locking of a pull-cord. x

.It is still another object of the invention to provide for a Venetian blind a cord-locking device in which a pull-cord is so controlled that inadvertent locking thereof is prevented.

It is a still further object of the invention to provide for a Venetian blind a cord-locking device in which the weight of an unextended por- 25 tion'oi the blind is adequate at all times to eflect further extension of the blind until a fully-extended condition thereoi'is achieved.

It is. also still another objector the invention to provide'ior a Venetian blind a cord-locking 3o device that requires but a single cord-releasing operation for each portion of the blind that is extended.

-It-is also a further object of the invention to provide for a Venetian blind a cord-locking dea vice which is exclusively controlle by an Opv erator foreflecting lockings of a pull-cord during lowering or extending movements of the blind. t,

In a preferred iormthe invention comprises a o sheave over which a cord istrained to efiect raising and lowering movements of a Venetian blind. Associated with the sheave is a. yoke provided with transverse corrugations that press the cord on thezperiphery of the sheave so as to 45 wedge 'the cord therebet ween for looking a blind in desired positions. Depending from the yoke is an integral portion that serves to guide the cord away from the sheave and toward a position suitable for an operator to produce thereby so desired mcvement'of the blind. Operatively connected with the yoke is a spiralled spring that actuates the yoke in a positive manner in a direction awayfrsm the sheave during all occasions ins-shying raising or towering movements of the blind. This permits a movement of the cord over the sheave under the exclusive control of an operator.

The invention will be more readily understood from the following description taken together withthedrawinginwhichz Fig. 1 is a perspective view showing the invention incorporated in a Venetian blind assembly;

Fig. 2 is a front elevation of the invention; Fig. 3 is a side elevation of the invention; Fig.iisaviewtakenalonglinesl-linl 'lg.2; Fig. 5 is a side elevation showing an alternate form of the invention, and

ldg.6isaviewtakenalcngth elines66in Fig. 5.

ReferringtoFigJaheaderbar llismoimted' inawindow casinginawellknown manner, not 'beneaththeheaderbarisatilt -fl bar il pro withasumorting member I! attachable thereto and formed with a journal". The tilt bar is rotatably supported on one end by disposingtheiournalllinabearingembodiedin an adjustable device 14, which is attachable t it the under surface of the header bar, and on the opposite end by a tilting m, not shown, which is preferably of the type disclosed in my Patent No. 2,108,939 issued Februagy 22, 1938. The adjustable device ll comprises a bracket i5 and a member I rotatably mounted thereon,

both of which cooperate to provide for the tilt.

bardropsof 1%and liinehesinthemanner disclosed in applicant's copending application,

Serial No. 196,335 flied March 17, 1938. It is understood that the slats and textile ladder forming the blind are ed and attached to the tiltbarin thewellknownmanner, and further that the longitudinal axisof-the journal I! coincides with the axis of rotation of the'tiit bar.

Acord-locking device 2. comprising a U-shaped memberflhavingspacedapartlegsofequal' msposedinalowerandrearwardportionof theU-shapedmemberisapinllon whichisrotatablymountedalockingyokett formed with a plurality of transverse corrugations 21 in an upperportion thereof. The locking yoke also includes an integral depending portion II which terminates in a substantiallyrectangular -opening2l. Theliftingcordpassesupwardfrom the hand-of an operator through the opening 20 toextendbetweentheperipheryofthesheave and the corrugations and to continue in a lefthand direction in a longitudinal groove 3 formed in the header bar. The lifting cord terminates in the blind, not shown, so that raising and lowering movements of the Venetian blind are accomplished in the well known manner.

Actuating the lifting cord raises or lowers the blind to desired positionsat each ofwhich it canbe "lockedbythecord sllghflyina counterclockwise direction (Fig. 1).. This -moves the locking yoke in the same direction causing the corrugations thereof to the lifting cord. As actuating force applied by an operator to the lifting cord is relaxed, the weight of the max-- tendedportionoftheblindcausesaforceoftension to be applied to the lifting cord. This tension functions in a direction opposite to the force initially originating with the operator and tends to actuate the lifting cord to move the locking yoke farther in a counter-clockwise or looking direction whereby the lifting cord is wedged between the corrugations and the periphery of the sheave. However, in order to lower the blind the operator supplies to the lifting cord a force to oppose the knee due to theweight of the unextended portion of the blind and in such magnitude that the tendency of the locking yoke to wedge the lifting cord is nullified. The force due hand of the operator is actuated in a clockwise direction (Fig. 1) and at the same time a relatively slight pulling force is applied thereto. This tends to move the locking yoke in a clockwise direction (Fig. 1) and, as a consequence thereof, the corrugations are moved out of engagement with-the portion of the lifting cord passing over the sheave. This allows the lifting cord free to move across the sheave. The pulling force supplied by the operator to the cord is then partially relaxed. This permits the weight of the lifting cord to be applied to the locking yoke substantially in the vicinity of the opening 29 as the lifting cord emerges therefrom (Fig. 1). As a result, the locking yoke is caused thereby to move in a counter-clockwise or locking direction (Fig. 1) and again'there is a tendency for the lifting cord to be wedged between the corrugations and the sheave to prevent fluther movement. of the lifting cord. Accordingly, there is a tendency to amt descent of the blind.

'Ihe above partial relaxation of pulling force on the part of the operator is an attempt to supply a force sufficient to oppose the force occasioned by the weight of the unextended portion of the blind so as to overcome the tendency of the locking yoke to wedge the lifting cord in the manner aforedescribed. Now, however, the force due to the weight of the unextendedv portion of the blind is so small that, as theoperator endeavors to upply an opposing controlling force in the manner mentioned above, the weight of the lifting cord is adequate to cause the locking .yoke to wedge the lifting cord on thesheave. Consequently, the blind is inadvertently locked in the three-quarter position due to this inadvertent wedging of the lifting cord. To move the blind therefrom to the fully extended position it will be u to quickly oscillate the portion of the lifting cord in the hand of the operator. This has the effect of intermittently freeing the lifting ment of the blind bly from the window casing. of course it is equally undesirable to overcome the previously described difliculty by pulling-up the blind to a substantial height and 75 then suddenly releasing the pull force to allow the blind to fall with a bang. Such inadvertent locking of the lifting cord is in the prior art an objectionable feature that is avoided in a manner that will now be explained.

Therefore, this invention contemplates a cordlocking arrangement in which the force due to the weight of an unextended portion of the blind will always be sumcient to cause a lowering of' the blind when pulling-force supplied by an operator to the lifting cord is relaxed for this purpose. plates a cord-locking apparatus wherein a positive force is permanently applied to the loclflng yoke 26 so as to normally. move the latter away from the cord-guiding sheave 24 to permit a free movement of the lifting cord thereover during all occasions involving a lowering of a Venetian blind from say, for example, a three-quarter to a complete extension. This amount is selected for the purposes of illustration and is understood to include any unextended portion that per se is unable to supply a force necessary to oppose that supplied by an operator so as to keep the locking yoke out of engagement with the lifting cord during lowering movements of the blind as mentioned above.

Referring to Figs. 3 and 4, a coiled spring 40 is mounted on transverse pin 25 in such manner that one free end engages the horizontal por tion 8 of the adjustable supporting device ll while the other free end 42 is suitably fastened to a right-hand leg 43 of the locking yoke 26.

As seen in Fig. 3 the spring tends-at all times to move the locking yoke 26 in a counter-clockwise or non-locking direction, that is, in a direction away from the cord-guiding sheave 24. The force inherent in the spring for this purpose is predetermined such that it will at least nullify the force due to the weight of the lifting cord applied to the portion 28 of the locking yoke 28 and tending :to cause an inadvertent locking of the blind in the manner described hereinbefore.

It is therefore contemplated that the spring should serve the purpose mentioned above during the interval when the force due to the weight of the unextended portion of the blind is relatively close to zero value. In other words, the spring functions to permit a free movement of the lifting cord over the cord-guiding sheave during the period when the force due to the unextended portion of the blind is inadequate to cooperate with the opposing force supplied by an operator to overcome or nullify the force due to the weight of the lifting cord and per se tending to cause an inadvertent wedgingiof the liftingcord in the manner aforementioned. It'is therefore evident that the weight of any unextended portion will now be adequate to cause the blind to drop to its complete extension during all occasions whenthe'lifting cord 'is actuated for the purpose of effecting a lowering movement of a Venetian blind. Accordingly, the nuisance and hazardous aspects hereinbefore mentioned are obviated.

Figs. 5 and 6 illustrate an alternate form of" the invention, As shown in Fig. 6a U -shaped member 50 islmounted in aligned openingsti, il

out as at 52 to permit a free movement thereof.

purpose of disposing oppositely projecting por- In other words, this invention contemassociated means.

scribed. That is to say that while certain clockwise or locking movement of the cord-locking member 26 is allowed the lifting cord is so controlled that such movement ls insuilicient to cause inadvertent wedging of the lifting cord by-the corrugations in the manner aforedescribed. Consequently, inadvertent locking of the blind is obviated.

It is understood that the invention is capable of modifications other than those disclosed herein, and the scope thereof together with such modifications is defined in the appended claims.

what is claimed is:

1. In a cord locking device fora Venetian blind comprising a header bar, a cord extending through I the header bar for raising and lowering the blind, means attachable to the header bar for guiding the cord, means associated with the guiding means for downwardly projecting the cord and responsive to actuations of the cord to cooperate with the guiding means to lock the cord for arresting movements of the blind; means moving the associated means in a direction opposite to the direction which a property of, the cord is tending to move the associated means thereby rendering the property of the cord ineffective to cause inadvertent cooperativeness between the guidin and associated means.

2. In a cord locking device for a Venetian blind comprising a header bar, a cord extending through the header bar for raising and lowering the blind, means attachable to the header bar for guiding the cord, means associated with the guiding means for downwardly projecting the cord and respon- -sive to actuations of the cord to cooperate with sociated means in a direction opposite to the direction of locking for retarding the responsiveness of the associated means to a property of the cord tending to move the associated means in a direction of locking to cause inadvertent cooperation between the guiding means and the 3. In a cord locking device for a Venetian blind comprising a header bar, a cord extending through the header bar for raising and lowering the blind, means attachable to the header bar for guiding the cord, means rotatably mounted on the guiding means for downwardly projecting thecord andresponsive to actuations of the cord to move toward. and away from the guiding means for locking and releasing the cord, respectively; means operatively associated with the rotatable means for causing. movement thereof away from the guiding means to compensate for a property of the cord tendingto move the rotatable means toward the guiding means to cause inadvertent locking of the-gcord. I

4. In a cord locking device for a Venetian blind comprising a header bar, a bracket attachable" to the header bar, a U-shaped member mounted on the=bracket, a sheave journalled in an upper.

from the sheave to preventinadvertent wedging of the cord in response to certain actuations thereof. v v r 5. In the cord locking device for a Venetian blind according to claim 4 in which the actuating means comprises a torsion spring 'operatively associated with the yoke.

6. A locking device for a Venetian blind comprising a .cord for actuating the blind, means.

for guiding the cord, means associated with the guiding means for downwardly projecting the cord and responsive to actuations of the cord for wedging the cord therebetween, and means actuating the associated means away from theguiding m'eans while at the same time a property of the cord is tending to move the associated means toward the guiding means to prevent inadvertent wedgingot the cord.

7. In a Venetian blind cord lock comprising a header bar, a cord extending through the header bar for raising and lowering the blind, means for locking the cord comprising an angle member fastened to an undersurface of the header bar at one end thereof, a -U-shaped member fastened to the angle member at an uppermost portionthereof and disposed at an angle relative to the header bar, a sheave mounted in an upper forward portion of the U- shaped member for guiding the cord, and a yoke pivotally secured to a lower rearward portion of the U-shaped member comprising an upper portion formed for accommodation on a peripheral portion of the sheave and provided with a plurality of transverse corrugations, and a lower portion for downward ly projecting the cord, the yoke being responsive to actuations of the cord to wedge the cord between a peripheral portion ofthe sheave and the transverse corrugations to lock the V'enetian blind in desired positions; means for moving the yoke in a direction opposite to the direction which a property of the cord is tending to produce movement thereof to prevent the property of the cord from inadvertently causing a wedging thereof.

WILLIAM WEAVER LEWIS. 

